Photovoltaic cells have been widely used in a variety of applications to generate convenient electricity. Typically, a single solar cell produces an output voltage of around 0.5V, and a plurality of cells, typically Silicon based, is conventionally connected in series to provide higher voltage levels. The solar cells are typically interconnected in solar-arrays, as described in PCT Published Application No. WO/2011/089607 filed on Jan. 23, 2011, by the same inventor as the instant application and which is owned in common, which is hereby incorporated by reference in its entirety.
A solar-array, having a crisscross network configuration, is typically embodied in a single solar module, wherein each solar-array module includes a multiplicity of solar cells. The solar modules are typically tilted towards the sun, and typically follow the path of the sun. However, at dawn and dusk, the angle of the sun is very low and one module may cast a shadow on a portion of a neighboring module, typically on the lower rows of cells of the solar-array module. Light may also be blocked or obstructed due to dust or snow, also typically proximal to the lower cells of the solar-array module. Thereby, the light obstruction causes a substantial reduction in the productivity of the module.
Solar array modules are often part of a solar system that includes a multiplicity of solar-array modules disposed in an array configuration. Reference is now made to FIG. 1 showing a prior art geometry of tilted solar modules of a solar-array module 100, tilted at an angle β this example, solar-array module 100a and 100b are disposed on a substantially horizontal surface, wherein solar-array module 100a is positioned in front of solar-array module 100b, with respect to the sun. When the sun is in a pitch angle of α above the horizon, solar-array module 100a having a length l, casts a shadow on the ground surface with a displacement of d, no shadow is cast over solar-array module 100b. But, when the sun is in a lower pitch angle than α, say α2, solar-array module 100a casts a shadow also over the lower section of solar-array module 100b. In this example, solar-array module 100a casts a shadow on the region delimited between P0 and P2 of solar-array module 100b, while only the solar cells disposed between P2 and P1 produce electric power.
Reference is also made to FIG. 2, schematically showing an example solar-array module 100 in horizontal placement, including crisscross network of solar cells 110. In this, example, solar-array module 100 includes 50 solar cells 110, arranged in 10 columns (“strings” 1-10) 130 and 5 rows (a-e) 120, wherein each column includes 5 solar cells 110, connected with interconnections 132, forming rows 120. If, for example, all 50 solar cells 110 are illuminated, solar-array module 100 produces 180 W over load R, with a combined current I of Imax (A). Unfortunately, the crisscross networking in this placement does not solve the light obstruction problem. When the solar cells 110 in a particular row of cells are overcast or otherwise in the shade, and thereby are not electrically active, each of the cells in that row of cells actually blocks transmission of electricity in the respective columns (string of cells) 120 of solar cells 110, thereby reducing the amount of energy that can be produced
The “crisscross” implementation relates to a previously described invention by the same inventor, published in PCT Published Application No. WO/2011/089607, which is hereby incorporated by reference as if fully described herein. A “crisscross” implementation is an electrical wiring configuration in which the electrical interconnections between cells are determined according to a regular grid pattern which interconnects all neighboring cells. By contrast, the presently claimed invention relates to electrical interconnections which are not necessarily determined according to a regular grid pattern.
However, the crisscross networking in the placement of the previously described invention does not solve the light obstruction problem. When the solar cells 110 in a particular row of cells are overcast or otherwise in the shade, and thereby are not electrically active, each of the cells in that row of cells actually blocks transmission of electricity in the respective columns (string of cells) 120 of solar cells 110, thereby reducing the amount of energy that can be produced.
For example, as shown in to FIG. 3a, when all of the solar cells 110 of a row 122 of example solar-array module 100, such as the bottom row 122e, for example only, are completely shaded (that is, the light is obstructed from reaching solar cells 110 of row 122e), the current in each string of cells 110 is OA, as the complete electric circuit cannot be formed. Although the crisscross configuration means that the solar cells 110 of each are also connected in parallel to respective solar cells 110 in adjacent strings, the current produced by each illuminated solar cell 110 has no pathway to load R since the respective solar cell 110 in row 122e blocks the electrical circuit. FIG. 3b schematically shows a variation of solar-array module 100, wherein solar-array module 100 operate with no obstructions. Current I flows through the strings 112 of solar cells 110. However, when the solar cells 110 of a row 122, such as the bottom row 122e, are completely shaded, as shown in FIG. 3c, the shaded cells 110 cut off the flow of current I.